For those who are too young to remember the game Buzz, it was a great simulation of the space race between USA and the former Soviet Union to be the first to land on the Moon.
That game introduces you the concept of risk management. Which I think will greatly improve the game and provides more realism.
Risk management is something that the space program have to deal everyday. Basically, a prototype component has great chances of failure and increases its reliability as it is tested and used. As the rocket becomes more complex and there are more steps in the space mission, the risk of failure increases exponentially.
In the real Apollo mission, they had to test every aspect of the mission to improve the reliability, the launch pad, lunar landing module, the docking sequence, a flight pass to the Moon, ... before Armstrong and Buzz step on the Moon.
In essence, you cannot play with big rockets, if you have not played with the smaller ones. Also, the reliability of the systems and subsystem can be compromised by thermal, aerodynamic stresses, hits etc...
Maybe it will be a great idea for a game expansion. What do you think?